Synthesis and catalytic activity of new supported rhodium(I) complexes for the enantioselective hydrogenation of methyl-(Z)-α-N-acetamidocinnamate

The polymerizable rhodium complex [(+)-diopRh(AAEMA)] (AAEMA−: deprotonated form of the ligand 2-(acetoacetoxy)-ethylmethacrylate) was obtained by reaction of (cod)Rh(AAEMA) with (+)-diop at −80 °C. Supported chiral complexes have been obtained by copolymerization of [(+)-diopRh(AAEMA)] with N,N-dimethylacrylamide and N,N′-methylenebisacrylamide or by reaction of [(+)-diopRhCl]2 with an opportunely prepared poly(β-ketoesterate). Catalytic tests carried out with the homogeneous catalyst or with both its heterogeneous analogues proved to be active in the enantioselective hydrogenation of methyl-(Z)-α-N-acetamidocinnamate yielding (S)-phenylalanine methylester with ee’s up to 67%.